I have, and also ones that cost about 50x as much. Sure, its not a spray gun you're going to use for the rest of your professional painting career, but for most of us working on our own cars its more than sufficient. Properly set up it can lay down a professional coat of paint. No, I wouldn't expect it to hold up for the next 20 years, but at $10 you can buy three or four, have them set up for all your various stages of paint, and throw them away when you're done. With a little practice no one will be able to tell you used a $10 gun instead of a $500 one.
Only thing it really needs is a good water separator, and for doing a whole car you'll have to refill the pot a few times because its only quart sized. Or buy a bigger one, or just buy a couple of guns and have them ready to go. For the price of the gun its cheaper just to buy a few than it is to buy extra pot's.
